N6923 accident description

NTSB description

HISTORY OF FLIGHT

On November 28, 1997, approximately 1810 eastern standard time, a Cessna 310R, N6923, was destroyed when it collided with trees and impacted mountainous terrain while on an instrument approach to the St. Mary's Municipal Airport (OYM), St. Mary's, Pennsylvania. The certificated commercial pilot and passenger were fatally injured. Instrument meteorological conditions prevailed for the personal flight that originated at Reading, Pennsylvania, at 1642. An instrument flight rules (IFR) flight plan was filed for the flight conducted under 14 CFR Part 91.

The purpose of the flight was to transport the passenger to St. Mary's for a hunting vacation. According to transcripts of communications from the Cleveland Air Traffic Control Center, the pilot was offered a weather observation from the controller upon initial contact at 17:32:35. The pilot responded, "I've got the AWOS [at OYM], what are you having?" The pilot was offered the weather observation at Bradford, 22 miles north of OYM, and he responded, "I'll go with the AWOS." The airplane was cleared for the Localizer/DME Runway 28 approach at OYM, at 17:41:50.

At 17:49:41, the pilot contacted Cleveland Center and advised he was unable to activate the runway lights on the UNICOM frequency, 122.7. He said, "I couldn't get the lights on twenty-two seven." The controller vectored the airplane for a second approach and issued a frequency change to Altoona Flight Service for possible assistance with the lighting. When the pilot re-established radio contact with Cleveland Center, he was cleared for the Localizer/DME Runway 28 Approach, at 18:05:37. The last radar plot of N6923 placed the airplane at 2,600 feet mean sea level (msl) in the vicinity of the final approach course, approximately 4 miles from OYM.

The airplane impacted trees and terrain on a ridge line with a peak elevation of 2,370 feet msl. The wreckage was below the top of the ridge at approximately 2,100 feet msl.

The accident occurred during the hours of darkness approximately 41 degrees 24 minutes north latitude, and 78 degrees 25 minutes west longitude.

PILOT INFORMATION

The pilot held a commercial pilot's certificate with ratings for airplane single and multi-engine land and instrument airplane. The pilot also held a flight instructor's certificate with ratings for single and multi-engine land and instrument airplane.

His most recent Federal Aviation Administration (FAA) second class medical certificate was issued on September 25, 1996.

The pilot's logbooks were not recovered, however, the pilot reported 11,000 hours of total flight experience on the date of his last FAA physical exam.

A co-worker examined company logs and reported the pilot's flight experience during the 90 days prior to the accident in the NTSB Form 6120.1/2. According to the report, the pilot flew 102 hours in the 90 days prior to the accident and 55 hours in the 30 days prior. Of the 55 hours reported in the previous 30 days, 53 hours were logged at night. The pilot logged 1.2 hours of night time in the 24 hours prior to the accident.

AIRCRAFT INFORMATION

The pilot's co-worker reported an annual inspection was performed on the airplane September 10, 1997, and the total time on the airframe was 6,970 hours as of November 4, 1997. She also reported the airplane was equipped with autopilot and a radar altimeter, both of which were disconnected.

METEOROLOGICAL INFORMATION

Weather at Dubois (DUJ), 24 miles southwest of OYM, was reported to be variable ceiling 100 feet and 1/4 mile visibility, with light drizzle and fog. The winds were from 260 degrees at 7 knots. The temperature was 47 degrees and the dewpoint was 45 degrees.

Weather at Bradford (BFD), 23 miles north of OYM, was reported to be measured ceiling 100 feet and 1 1/4 mile visibility with mist. The winds were from 290 degrees at 7 knots. The temperature was 43 degrees and the dewpoint was 43 degrees.

AIDS TO NAVIGATION

The pilot requested and was vectored for the Localizer/DME Runway 28 approach at the St. Mary's Municipal Airport (OYM), St. Mary's, Pennsylvania. The localizer frequency was 108.9. The inbound course was 280 degrees and the minimum descent altitude (MDA) for the final segment of the approach was 2,460 feet.

A DME transmitter was located on the airport. DME fixes along the localizer course established the final approach fix and all stepdown fixes.

The final approach fix for the LOC/DME RWY 28 approach at OYM was at the LYCEE intersection, which was positioned at 6 DME on the localizer course. The minimum descent altitude prior to crossing LYCEE was 3,600 feet. The next stepdown fix was at 2.7 DME. The minimum descent altitude for the segment of the Localizer/DME Runway 28 approach between 6 DME and 2.7 DME was 2,680 feet msl. The MDA from 2.7 DME to the missed approach point (MAP) at .8 DME was 2,460 feet. All stepdown fixes and the missed approach point were established by DME only, on the localizer course.

At the time of the accident, there was no one at the airport to brief the pilot about weather or the altimeter setting. The automated weather observation service (AWOS) at OYM was published out of service and broadcast in the Test mode. The AWOS announced "Test" at the beginning of each observation broadcast.

In the remarks section of the approach plate for the LOC/DME RWY 28 approach at OYM it stated:

"Obtain local altimeter on CTAF/AWOS, when not available, procedure not authorized."

The weather reporting equipment in the airport office was observed on November 30, 1998. The altimeter setting was 29.97 while the test message on the AWOS broadcast an altimeter setting of 29.56.

The elevation for the St. Mary's Municipal Airport was 1,934 feet.

COMMUNICATIONS

Examination of Air Traffic Control records from Cleveland Center revealed that during both approaches the controller repeatedly referred to the "outer marker." A review of the approach plate revealed there was no outer marker associated with the LOC/DME Runway 28 approach at OYM. The controller stated that the outer marker was located at LYCEE, the final approach fix, at 6 DME on the localizer.

At 1741:50, N6923 was advised he was approximately 14 miles from LYCEE and cleared for the LOC\DME Runway 28 approach. At 1749:15, approximately three miles before reaching LYCEE, and 8 miles from the airport, N6923 advised he was unable to activate the runway lights and received vectors for a second approach.

During the second approach, at 1805:29, the pilot stated, "...six nine two three just picked up the DME show me uh show me eleven point eight out..."

At 1806:21, when the airplane was approximately 10 DME on the localizer, the controller stated,"...and november six niner two three you should be over LYCEE about now."

The controller amended his estimation of the airplane's position at 1807:53. He stated,"...november six niner two three uh the outer marker is ah two point three miles away."

The pilot repeatedly reported the loss of the DME signal.

WRECKAGE INFORMATION

The wreckage was examined at the site on November 30, 1997. All major components were accounted for at the scene. The airplane contacted trees on ascending terrain. The airplane came to rest at the point of initial ground contact on an up-slope of approximately 30 degrees. The distance from the first tree strike to the final piece of wreckage was 172 feet. The wreckage path was oriented 279 degrees magnetic and divided into 1 foot increments called wreckage points (WP).

The first tree strike (WP zero) broke the trunk at a point approximately 45 feet above the ground. The second tree strike was at WP 63. The second tree was approximately 24 inches in diameter and the trunk was broken off at a point approximately 30 feet above the ground. The trees at WP zero and WP 63 were broken off at points approximately the same altitude msl.

The right wing, right main landing gear, and the right elevator were at WP 106. The right elevator was 12 feet left of centerline.

The main wreckage was at the initial point of ground contact at WP 151. The left engine with propeller attached and the right engine were free of their mounts and entangled in the wreckage. The nose gear and left main landing gear were down and locked and attached to the wreckage. The right propeller was at WP 172, 30 feet right of centerline. All propeller blades displayed similar twisting, bending, leading edge gouging, and chordwise scratching.

The cockpit and cabin areas were destroyed by impact and consumed by post-crash fire. Control cable continuity was established from the cockpit to the tail section. Control continuity to the wing surfaces could not be established due to impact and fire. All cockpit instrumentation and controls were destroyed by impact and fire.

MEDICAL AND PATHOLOGICAL INFORMATION

An autopsy was performed on the pilot by Dr. Eric Lee Vey of the Erie County Coroner's Office, Erie County, Pennsylvania.

The toxicological testing report from the FAA Toxicology and Accident Research Laboratory, Oklahoma City, Oklahoma, revealed negative for drugs and alcohol for the pilot.

TESTS AND RESEARCH

On December 11, 1997, the engines were examined at the Allegheny County Airport, West Mifflin, Pennsylvania. The #2, #4, and #6 rocker covers of the right engine were separated from the engine by impact and the engine could not be rotated by hand. The magnetos were separated from their mounts. The right magneto sustained impact damage and was not tested. The left magneto produced spark at all terminal leads. The #2 top and the #4 bottom spark plugs were destroyed by impact. The electrode of the #4 top plug was damaged. The remaining spark plug electrodes were intact and light tan and gray in color. The fuel flow divider was disassembled. The screen was clean and absent of debris.

The engine crankcase was split and the main bearings and saddles were wet with oil. The bearings and saddles were in place and exhibited no anomalies. The pistons and cylinders exhibited no pre-impact anomalies.

The left engine was rotated by hand and continuity was established through the valvetrain and accessory sections. Compression was verified using the thumb method. Both magnetos were tested and produced spark at all terminal leads. The top spark plugs were removed and the electrodes were intact and light tan and gray in color. The fuel flow divider was disassembled. The screen was clean and absent of debris.

Both propellers were examined at McCauley Propeller Systems, Vandalia, Ohio, under the supervision of an FAA inspector. According to the inspection report:

"Both propellers were operating under the conditions of some power at impact. Propeller damage for both propellers was very similar indicating equivalent energy at impact."

A recorded radar study performed by the NTSB Office of Research and Engineering revealed that during both approaches, N6923 descended below the MDA for each segment of the approach flown. During the first approach N6923 was depicted at 2,200 feet at a point approximately 10 DME; 1,400 feet below the published MDA of 3,600 feet for that segment and 260 feet below the lowest MDA for the approach.

Examination of the voice communications between N6923 and Cleveland Center revealed that on at least two occasions the pilot announced his indicated altitude, at 6,000 feet and 4,000 feet msl respectively. Time comparisons between the voice communication data and the radar data revealed the altitudes announced by the pilot were identical to those depicted by the radar data.

A flight inspection of the Localizer/DME Runway 28 approach at OYM was performed by the FAA on December 1, 1998. According to the flight test report, the facility operation was found to be satisfactory.

ADDITIONAL INFORMATION

In the United States Army Field Manual for Instrument Flying and Navigation for Army Aviators (FM 1-240), under Stepdown fixes in nonprecision approaches, it stated: "A stepdown fix may be provided on the final, such as between the final approach fix and the airport for the purpose of authorizing a lower MDA after passing an obstruction. This stepdown fix may be made...by DME. If the stepdown fix cannot be identified for any reason, the altitude at the stepdown fix becomes the MDA for a straight-in landing."

According to the FAA Instrument Flying Handbook (AC 61-27C): "Appropriate maneuvers, which include altitudes, courses, and other limitations, are prescribed in these procedures. They have been established for safe letdown during instrument flight conditions as a result of many years of accumulated experience. It is important that all pilots thoroughly understand these procedures and their use."

"VOR/DME procedure number means that both operative VOR and DME receivers and ground equipment in normal operation are required to use the procedure. As previously stated, in the VOR/DME procedure, when either the VOR or DME is inoperative, the procedure is not authorized."

In the Aeronautical Information Manual under Instrument Approach, it stated: "Pilot-1. Be aware the controller issues clearance for approach based only on known traffic. 2. Follow the procedure on the IAP, including all restrictive notations such as: Procedure not authorized when local area altimeter not available."

The airplane wreckage was released on November 30, 1997, to the manager of the St. Mary's, Pennsylvania Airport.